wT 2858/02
Page 22
11.1.2
Welding Instructions for Long Design (KHA-SL)
At a distance of 20 mm from the edge of the body, a temperature of +200 °C may not
be exceeded. Carry out temperature checks. Cooling the ball valve body during welding
is advisable. Following cooling down, the tightening torques of the connection screws
must be checked against the values from the table.
12
Service and Maintenance
Maintenance and inspection intervals are to be determined by the operator dependent
on the operating mode, as these valves can be utilized under a number of different
operating conditions.
In order to increase service life at low activation counts, we recommend carrying out an
activation from time to time. For this purpose it is fully sufficient to only shift the ball by a
few angular degrees.
Maintenance and inspection work may only be carried out by trained personnel.
Prior to the start of service and maintenance work, it must be ensured that the pipeline
system is depressurized and that no medium residues are contained within.
In the event of possible leakages to the atmosphere, the tightening torques at the affected
positions must be checked against the values of the tightening table.
When removing an actuator, it is necessary to protect it against rotation prior to
loosening of the connecting screws.
12.1
Seal Replacement
!
ACHTUNG
Prior to installation, all individual parts, especially seals and sealing
surfaces, must be carefully checked and replaced if damaged. Visible
contamination on the machined surfaces must be cleaned off.
12.1.1
Seal Replacement on the Operating Stem
»
Bring the valve into the OPEN position
»
Depressurize the line
»
Remove the valve from the line
»
Remove the body connection screws
»
Remove sealing elements and supporting rings (to the extent present) from the
body midsection
»
Bring the ball into the CLOSED position and remove it
»
Remove the handle
»
Remove the stuffing box nut
»
Remove the operating stem and the washer
»
Remove the Belleville spring washer, dis, washer, pressure ring and antistatic disc
»
Remove the stuffing box and replace with a new one
»
Inspect washers and if necessary, replace
»
Assemble in reverse sequence (tightening torques in accordance with table)
»
Function test
